Flow cell comprising a storage zone and a duct that can be opened at a predetermined breaking point

ABSTRACT

A flow cell having at least one storage zone connected to a duct for conducting fluid out of, into or/and through the storage zone. The duct includes a duct section which is delimited by a substrate and a film joined to the substrate and in which the duct is sealed and can be opened at a predetermined breaking point by deflecting the film. The film covers a recess in the substrate which forms the duct section. A sealing wall that seals the duct and is integrally joined to the substrate is placed in the recess. The predetermined breaking point is formed by a breakable joining region between the film and an edge portion of the sealing wall facing the film. The dimensions of a peripheral area of the sealing wall which is formed in the edge portion and runs parallel to the film determine the surface area of the joining region.

The invention relates to a flow cell, in particular for analyzing or/andsynthesizing substances, having at least one storage zone which isconnected to a duct for transporting fluid from, into, or/and throughthe storage zone, wherein the duct has a duct zone that is delimited bya substrate and by a flexible film which is connected to the substrate,in which duct zone the duct is closed off and at a predeterminedbreaking point is openable while deflecting the film.

A flow cell of such type in which the duct is connected to a storagechamber that is to be emptied by way of the duct is derived from WO2009/071078 A1. The storage chamber is formed by a thermoformed zone ofthe otherwise planar film that delimits the duct zone. The film iscomposed of an aluminum layer having a plastics coating that faces theinternal side of the storage chamber. Outside the storage chamber andthe duct zone, and at the predetermined breaking point, the film isadhesively bonded or/and welded to a planar surface of the substrate orto a further film that covers the latter.

The predetermined breaking point that is established by welding or/andadhesive bonding between the plastics coating of the film and the planarsurface of the substrate, in terms of the planar extent of the former,is capable of being metered only with great difficulty. Influencescaused by variations result above all from the behavior of the plasticscoating of the film during welding, from the distribution of thetemperature generated by a welding tool, from the achievable weldingtrack width of approx. 1 mm, from the accuracy in positioning thewelding tool and thus from the reproducibility of the spacing of thepredetermined breaking point from the storage zone. The force requiredfor rupturing the predetermined breaking point varies accordingly in anundesirable manner.

The invention is based on providing a new flow cell of the typementioned at the outset, having a duct zone that has a predeterminedbreaking point, wherein the force for rupturing the predeterminedbreaking point is in a tighter tolerance range.

This object is achieved according to the invention in that the filmcovers a clearance in the substrate that forms the duct zone, and abarrier wall which is integrally connected to the substrate and whichshuts off the duct is disposed in the clearance, that the predeterminedbreaking point is formed by a rupturable connection zone between thefilm and a peripheral portion of the barrier wall that faces the film,and that the dimensions of a peripheral area of the barrier wall that isparallel with the film and is formed in the peripheral portion arerelevant to the planar extent of the connection zone.

By way of concentrating the connection zone that forms the predeterminedbreaking point according to the invention to the peripheral area of thebarrier wall that reaches up to the film, the connection zone,independently of the welding conditions, has a defined extent andposition. Variations in the force required for rupturing thepredetermined breaking point are accordingly minor.

As is explained below, the mentioned peripheral area may approximate aline that is perpendicular to the flow direction of the fluid.

Preferably, the duct is openable by way of a fluid pressure that bearson the predetermined breaking point, or by way of mechanical or/andpneumatic deflection of the film. While a fluid pressure may be built upe.g. by squeezing a storage chamber having a flexible film wall, anoperating apparatus that is provided for the flow cell may be employedfor mechanically or/and pneumatically rupturing the predeterminedbreaking point.

It is to be understood that the film at the peripheral portion may beadhesively bonded or/and welded to the peripheral area of the barrierwall. Alternatively or additionally, a releasable clamping connectioncould be established by way of a clamping element that acts on the filmand is movably connected to the flow cell.

The barrier wall is preferably produced in one operational step,conjointly with the injection molding of the substrate.

In one particularly preferred embodiment of the invention, theperipheral area of the barrier wall terminates flush with the openingperiphery of the clearance that is formed in the substrate. In this wayit may be ensured that the barrier wall by way of the peripheral portionthereof that faces the covering film reaches up to the film, and thatthe film may be adhesively bonded or/and welded in one operational stepto both the substrate as well as to the peripheral portion of thebarrier wall.

While it is possible for the barrier wall to be configured so as to beannular, while blocking a corresponding radial fluid flow, the barrierwall in the preferred embodiment is configured as a barrier web thattraverses the clearance in the substrate, said barrier web at the endsthereof being connected to the substrate.

The thickness of the barrier wall preferably decreases toward thecovering film, in particular in such a manner that the film bears on theperipheral portion of the barrier wall in only a linear manner.

Accordingly, the barrier wall in the cross section may be configured soas to be triangular or segment-shaped. In one further embodiment, theperipheral portion of the barrier wall bears on the film by way of aflattening. The length of the flattening in the flow direction, and thusthe length of the predetermined breaking point in this direction, ispreferably less than 0.5 mm, in particular less than 0.1 mm, optionallyless than 0.05 mm.

The clearance preferably opens toward a planar area of a preferablyplate-shaped substrate, and the film that covers the clearance ispreferably a planar film.

In one further embodiment of the invention, the duct, in that duct zonethat has the predetermined breaking point, in relation to duct zonesthat are adjacent thereto, is widened or constricted in the crosssection. The barrier web can be lengthened or shortened accordingly.Since the rupture force of the predetermined breaking point depends onthe geometry of the connection zone between the film and the barrierweb, the rupture force may be set by a suitable choice of the wideningor the constriction. The rupture force exerted by a mechanical actuatorthat compresses the storage zone is preferably less than 20 N, inparticular less than 10 N, optionally less than 5 N.

The predetermined breaking point in the case of a projection that isperpendicular to the plate plane of the substrate preferably lies in theprojected zone of the storage chamber. In this space-saving embodimentthe storage chamber is optionally located on one side of theplate-shaped substrate, while the clearance that forms the duct zone isdisposed on the other side of the plate.

In particular in the case of the latter embodiment, the storage chambermay be composed of a film that has an aluminum layer having a plasticscoating that faces the internal side of the storage chamber, wherein theplastics coating is applied in a planar manner to the substrate bywelding or adhesive bonding, and the predetermined breaking point isformed between the plate-shaped substrate and a cover film fromplastics, preferably from the same plastics as the substrate. Thermalwelding, ultrasonic welding, or laser welding may be considered forproducing the predetermined breaking point from identical plasticsmaterial, for example.

In a further design embodiment of the invention, the duct may have aplurality of predetermined breaking points, and a functional element ofthe flow cell, such as a drying reagent, for example, may in particularbe disposed downstream of a predetermined breaking point.

Moreover, the drying reagent may be enclosed between two predeterminedbreaking points.

A film that delimits the storage chamber may be identical to a film thatdelimits the duct zone, in particular when the storage chamber and aduct zone that is connected to the storage chamber are both disposed onone side of a plate-shaped substrate.

The invention will be explained in more detail hereunder by means ofexemplary embodiments and of the appended drawings which refer to theseexemplary embodiments. In the drawings:

FIG. 1 shows a flow cell having a plurality of fluid transport ductsaccording to the invention, in a front view;

FIG. 2 shows the flow cell of FIG. 1 in a rear view, without a coverfilm;

FIG. 3 shows a duct zone of a transport duct of the flow cell of FIG. 1,having a predetermined breaking point, partially without a cover film;

FIG. 4 shows various exemplary embodiments of a fluid storage unit thatis usable in a flow cell, having a transport duct according to theinvention that is connected to the fluid storage unit;

FIG. 5 shows three further exemplary embodiments according to theinvention, for configuring predetermined breaking points in transportducts;

FIG. 6a shows a transport duct having two predetermined breaking points;

FIG. 6b shows a transport duct having an annular predetermined breakingpoint;

FIG. 7 shows transport ducts according to the invention, having a dryingreagent that is disposed so as to be adjacent to the former;

FIG. 8 shows transport ducts having predetermined breaking points whichmay be ruptured by external actuators;

FIG. 9 shows a transport duct according to the invention that isconnected to two storage chambers;

FIG. 10 shows transport ducts according to the invention, for filling astorage space of a flow cell;

FIG. 11 shows storage units which are provided to be partially filled bytransport ducts according to the invention.

A microfluidic flow cell, shown in FIG. 1, which is connectable to anoperating apparatus (not shown) comprises a substantially plate-shapedsubstrate 1 which is integrally produced from plastic by theinjection-molding method, for example from PP, PE, COC, PC, PMMA, orfrom a mixture of these plastics.

The substrate, on the side thereof that is visible in FIG. 1, by way ofpart of its plate area is adhesively bonded or/and welded to a film 2.On that side of the substrate 1 that faces away from the former, theentire plate area is connected to a planar film 3 which covers and shutsoff clearances in the substrate 1 that are open toward this plate area.

Thermoformed zones of the film 3 in the example shown form three storagechambers 4, 5, and 6 for receiving reagent liquids. The film 2 iscomposed of an aluminum-plastics laminate, the aluminum layer thereofthat points toward the outside forming a vapor barrier to the reagentliquids in the storage chambers.

The cover film 3 in the example shown is composed of the same plasticsmaterial as the substrate 1, or else optionally of an aluminum-plasticslaminate.

As is shown in FIG. 2, the storage chamber 4 by way of a duct 7 isconnectable to a chamber 10 for receiving a specimen substance to beexamined. The specimen chamber 10 in turn by way of a duct 11 and areaction or detection zone 12 for examining the specimen substance isconnected to a waste chamber 13. The storage chambers 5 and 6 by way ofducts 8 and 9 may be connected to the duct 11.

The ducts 7 and 9 each have a widened duct zone 14, separatelyillustrated in FIG. 3, in which the duct in the flow direction is closedoff and an unlockable predetermined breaking point is formed.

A clearance 15 which forms the respective duct zone 14 and is relevantto the size of the duct cross section is traversed by a barrier web 16that in the example shown has a triangular cross section. A peripheralportion 17 of the barrier web 16 that faces the cover film 3 is flushwith the planar plate area 18 of the substrate 1 that is adjacent to theclearance 15, and is connected to the cover film 3. The barrier web 16that is integrally connected to the substrate 1 in this way completelyblocks the respective duct.

The cover film 3, which is adhesively connected or/and welded to thesubstrate 1, in the zone of the peripheral portion 17 is also connectedto the barrier web 16, wherein this connection forms a rupturablepredetermined breaking point. In the case of a prevalent fluid pressurethat may be generated by compressing a thermoformed zone of the film 2and by squeezing the respective storage chamber 4, 5, or 6, theconnection between the barrier web 16 and the cover film 3 is ruptured,while deflecting the cover film 3.

The peripheral portion 17 of the barrier web 16 forms a connection zonethat in terms of the dimensions thereof is defined and that enables areproducible closure strength and thus reliable rupturing of thepredetermined breaking point at a specific fluid pressure. The length ofthe peripheral portion 17 is preferably <0.5 mm, in particular <0.1 mm,optionally even <0.05 mm.

In the example shown, the film 3 is adhesively bonded or/and welded tothe barrier web 16. Additionally or alternatively, a clamping connectionbetween barrier web 16 and cover film 3 is also to be considered, as isdiscussed further below.

For the sake of simplicity, further details of the flow cell shown inFIGS. 1 and 2 are not described herein. It is to be understood that aflow cell having a duct of the type as is included in a pluralitythereof in the flow cell of FIGS. 1 and 2 may also be constructed in amanner entirely different from that of the flow cell shown in FIGS. 1and 2, and in the extreme case may, for example, have a duct of thistype only as a singular functional part.

FIG. 4 in fragments shows flow cells having a storage chamber 19 and aduct 20 having a predetermined breaking point on a barrier web 16. Thestorage chamber 19 is delimited by a film 2 which is adhesively bondedor/and welded to a plate-shaped substrate 1 on one side of the latter. Acover film 3 that is adhesively bonded or/and welded to the plate-shapedsubstrate 1 on the other side of the latter, while delimiting the duct20, shuts off a duct clearance 15 in the substrate 1 that is connectedto the storage chamber 19.

According to FIG. 4A, an actuator ram 22, acting on a thermoformed zone21 of the film 2 that forms the storage chamber 19, of an operatingapparatus (not shown in more detail) in terms of the dimensions of saidactuator ram 22 is configured so as to be narrower than the thermoformedzone 21, such that the latter laterally buckles in a defined manner whenfluid is squeezed out of the storage chamber 19, thus enabling acontrolled buildup of pressure for opening the predetermined breakingpoint.

In a projection that is perpendicular to the plate plane of thesubstrate 1, the barrier web 16 is located in the duct 20 within theprojected zone of the storage chamber 19. The storage unit and thepredetermined breaking point may thus be accommodated in a space-savingmanner in a narrow zone of the flow cell.

In the case of the exemplary embodiment of FIG. 4b , a storage chamber19 between a film 2 and a substrate 1 is not formed by a thermoformedzone 21 of the film 2 alone, but also by a clearance 24 in thesubstrate. The clearance 24 and the geometry of the actuator ram 22 arechosen such that complete emptying of the storage zone is possible inthat the film 21 in the terminal position of the actuator ram 22 isdeformed such that said film 21 largely bears on the contour of theclearance 24. For this purpose, the contour of the actuator ram 22 inrelation to the contour of the clearance 24 is recessed by a factorcorresponding to double the thickness of the film 2.

According to the exemplary embodiment of FIG. 4c , such a clearance 24in the substrate 1 is singularly relevant to the volume of a storagechamber 19.

The exemplary embodiment of FIG. 4d corresponds to the exemplaryembodiment of FIG. 4a . A movable element 25 may be retained manually orby an operating apparatus in a closure position, or said movable element25 is fixedly yet releasably connected by means not shown, such as byundercuts or snap-fit closures, to the substrate 1 such that thepredetermined breaking point on the barrier web 16 is impossible to beforced open by a buildup of pressure in the duct 20 with the aid of anactuator ram 22. The predetermined breaking point may only be rupturedin a position in which the element 25 is retracted from the retainingposition shown in FIG. 4d . The element 25 may be retracted manually orby the operating apparatus. When the movable element 25 is used,adhesive bonding or welding of the predetermined breaking point may bedispensed with. By retracting the element 25, the force required forunlocking the predetermined breaking point is reduced by the amount thatwould be necessary for rupturing a welded or adhesively bondedconnection.

The exemplary embodiment of FIG. 4e corresponds to the exemplaryembodiment of FIG. 4c , except for a further film 26 which forms a vaporbarrier to fluid that reaches the duct 20 from the storage unit 19. Thefilm 26 is composed of aluminum, for example, and has an integratedadhesive layer that is sensitive to pressure, for example.Alternatively, the film 26 may be connected to the film 3 only in alocalized manner and not in the zone of the predetermined breakingpoint.

Such a barrier film 26 is advantageous in particular in the case of theexemplary embodiment of FIG. 4f , in which a storage chamber 19 isformed by a clearance 24 that continues through a substrate 1, thestorage content thus coming into direct contact with the cover film 3. Aduct portion 23 that connects the storage chamber 18 to the clearance 15may be omitted in the case of the exemplary embodiment of FIG. 4 f.

Exemplary embodiments shown in FIG. 5 correspond to the exemplaryembodiment of FIG. 4c , except for the design of the cross section of abarrier web that forms the predetermined breaking point.

According to FIG. 5a , a barrier web 16 a in the cross section is notconfigured so as to be triangular but semicircular. In the case of sucha cross section, the barrier web also bears on the cover film 3 in alinear manner. Such a barrier web during injection molding of thesubstrate 1 may advantageously be produced at a lower injection pressurethan a barrier web that is triangular in the cross section.

FIG. 5b shows a barrier web 16 b having a flattening that faces thecover film 3. The flattening forms a planar peripheral area of thebarrier web 16 that is parallel with the film 3, wherein this peripheralarea is congruent with a connection zone between the film 3 and thebarrier web 16, the connection zone forming a predetermined breakingpoint. The front and the rear edge of the flattening, when viewed in theflow direction, delimit the connection zone.

In the case of the exemplary embodiment according to FIG. 5a theperipheral area of the barrier web 16 that is parallel with the film 3is in each case approximated to a line which extends in a transversemanner to the direction of the fluid flow.

FIG. 5c shows a barrier web 16 c having a peripheral portion 17 c thatfaces the film 3 (not shown), on which peripheral portion 17 c aperipheral web 40 that in relation to the remaining barrier web isnarrower and that has a correspondingly narrow peripheral area 41 thatis parallel with the film 3 is formed. Such a step-shaped barrier webmay advantageously be produced at low tooling complexity by theinjection-molding method. The peripheral area 41 that is parallel withthe film 3, in the longitudinal center of the peripheral web 40, has abulge 42 that is formed by a protrusion of the peripheral web 40. Thisbulge 42, projecting counter to the flow direction, during rupturing ofthe predetermined breaking point forms an initial zone which promotessymmetrical rupturing of the predetermined breaking point from the webcenter toward the sides, thus contributing toward high reproducibilityof the force that is required for rupturing the predetermined breakingpoint.

FIG. 6a shows an exemplary embodiment which largely corresponds to FIG.4c but in the case of which two predetermined breaking points instead ofonly one are formed by two barrier webs 16 and 16′. Particularly tightclosure of the storage chamber 19 may be achieved by the twopredetermined breaking points. The fluid pressure that is required forrupturing the predetermined breaking point may be dissimilar, that is tosay be higher for the second predetermined breaking point at 16′ thanfor the first predetermined breaking point at 16, for example, thisbeing adjustable potentially by way of dissimilar widths of thepredetermined breaking points, for example.

FIG. 6b shows an exemplary embodiment which is similar to that of FIG.4c , in which, deviating from the latter, the opening of a duct portion23 that connects the storage chamber 19 to the clearance 15 issurrounded by an annular barrier web 16 a. The annular barrier web 16 amay be configured as an entire ring or as a segment of an entire ring.

FIG. 7 shows exemplary embodiments in which a drying reagent 27 isdisposed downstream in a duct 20 of a predetermined breaking point. Thisdrying reagent may advantageously be suitably re-dissolved by way of aliquidizing reagent that is retrieved from a storage chamber 19. Priorto the predetermined breaking point being opened, the drying reagent isexpediently isolated from the storage chamber 19.

In the case of the exemplary embodiment of FIG. 7b , a predeterminedbreaking point, which is formed by a further barrier web 16′, is yetagain disposed downstream of the drying reagent. On account thereof,environmental influences are kept away even more effectively from thedrying reagent during storage.

FIG. 8 in fragments shows exemplary embodiments of flow cells, in whichseparate installations for rupturing a predetermined breaking point thatis formed by a barrier web 16 are provided.

In the case of the exemplary embodiment of FIG. 8a , a weak spot isformed in a substrate 1 by way of a clearance 28 in such a manner that acover film 3 by way of a protrusion 29 according to the dashed line 30may be deflected with the aid of an actuator ram 22, and thepredetermined breaking point which is formed at 16 may be ruptured, orin the case of an opened predetermined breaking point the throughflowcross section of the duct 20 may be enlarged, respectively. Inparticular, emptying of the storage unit 19 may be performed at lowpressure by way of this separate opening action of the predeterminedbreaking point. Moreover, the flow resistance of the predeterminedbreaking point may advantageously be regulated when the latter isopened.

In the case of the exemplary embodiment of FIG. 8b , an inlet duct 31for a pressurized gas that deforms the substrate in a correspondingmanner is formed instead of a mechanical actuator ram 22.

In the case of the exemplary embodiment of FIG. 8c , two weak spots fordeflecting a film 3 are provided so as to be disposed ahead and behind apredetermined breaking point, when viewed in the flow direction, whereinclearances 28 and 28′ that form weak spots are interconnected by way ofa duct 32. A film 2 may be dented by actuator ram 22 and 22′ such that agas pressure that deforms the substrate 1 and deflects the film 3according to the dashed line 30 is created in the clearances 28, 28′.

The exemplary embodiment of FIG. 8d , having only one clearance 28 andone actuator ram 22, operates based on the same principle.

FIG. 9 shows an exemplary embodiment having a storage chamber 19 and afurther storage chamber 19′. A deformation of a film 2 by way of anactuator ram 22 leads to a buildup of pressure in the chamber 19′ andthus to two predetermined breaking points that are formed by barrierwebs 16 and 16′ being opened. The transport of reagent from the storagechamber 19 thereafter, by virtue of the already opened predeterminedbreaking points, may be performed in a more controlled manner and atlower pressure.

FIG. 10 in fragments shows flow cells having a storage chamber 33 thatis only partially filled with a fluid 34, the former being isolated byway of a barrier web 16 that forms a predetermined breaking point. Thestorage chamber 33 may be filled with a further fluid, for example afluid to be analyzed, by way of a duct 20. In the case of a pressurebuildup by an inflowing fluid as indicated according to the arrow 35, apredetermined breaking point that is formed on the barrier web 16 isruptured. In the case of a further pressure buildup, the gas of theair-filled or gas-filled part-zone of the storage space 33 is initiallycompressed, the fluid reaching the storage space where said fluid maymix and optionally react with the fluid 34 that is stored in saidstorage space. After filling, a drop in pressure leads to the compressedair escaping in the direction that is counter to the arrow 35. This maybe simultaneously performed by a plurality of storage zones 33 if andwhen the adjacent duct zones 20 thereof are connected to a pressuresource and to a fluid source. After filling and the buildup of pressure,the fluid mix is prevented from flowing back by the barrier web 16.

The volume of the storage chamber 33 is in part formed by a continuousclearance 24 in a substrate 1, and furthermore by a thermoformed zone 21of a film 2 which may be composed of an aluminum-plastics laminate oronly of plastics, and may be produced by injection-molding.

The storage chamber 33 in the case of the exemplary embodiment of FIG.10b contains a drying reagent 37.

The exemplary embodiment of FIG. 10c differs from the exemplaryembodiment of FIG. 10a in that the storage volume of the storage chamber33 is formed exclusively by a substrate 1 having a bulge 36.

Such a bulge is absent in the case of the exemplary embodiment of FIG.10d . A clearance 24 in the plate-shaped substrate 1 which is open onone side is exclusively relevant to the volume of the storage chamber33.

In the case of the exemplary embodiment of FIG. 10e , the clearance 24is continuous, and is covered on both sides by a film 2 or 3,respectively.

In the case of an exemplary embodiment shown in FIG. 11, a storagechamber 33 is partially filled with a fluid 34. A pipeline 37 which issubmerged in the fluid 34 protrudes into the storage chamber 33. Thepipeline 37 is connected to a duct 20 that is closed off by a barrierweb 16.

After a predetermined breaking point that is formed on the barrier web16 has ruptured, a specimen fluid to be examined by way of the duct 20and the pipeline 37 may be directed into the storage chamber 33 wherethe specimen fluid comes into contact with a fluid 34 that forms areagent.

A conveying pressure that bears on the specimen fluid in order for thepredetermined breaking point to be ruptured, after opening the latter,ensures that the air that when viewed in the flow direction is locatedbehind the barrier web 16 in the duct 20 and the pipeline 37 isdisplaced, said air rising in the fluid 34. Specimen fluid that finallyenters the storage chamber 33, due to a compression of the air above thefluid level of the fluid 34, ensures a buildup of pressure in thestorage chamber 33.

In the case of the conveying pressure being reduced, a mixture of thespecimen fluid and of the reagent fluid 34 therefore flows back into thepipeline 37 and optionally into the duct 20. By way of alternatinglyincreasing and lowering the conveying pressure the mixture may be movedaccordingly and be further homogenized by the movement.

By way of further lowering the conveying pressure, the mixture by way ofthe pipeline 37 and of the duct 20 may finally be discharged to a partof the flow cell that further processes said mixture, or the latter forthe purpose of analysis, for example a visual analysis, remains in thestorage chamber 33.

The same construction of a storage chamber may also be used forre-suspending a drying reagent such as the drying reagent 37 of FIG. 10bthat is provided in the storage chamber.

The construction according to FIG. 11 may also be utilized merely foremptying the storage chamber 33, in that pressurized gas is infed by wayof the duct 20 and is compressed above the fluid level in thestorage-chamber zone. The pressurized gas may subsequently force thefluid 34 out of the storage chamber 33 for evacuation into the pipeline37 and into the duct 20.

A film 21 that forms the storage unit may be configured so as to beelastically deformable such that the volume of the storage chamber 33may be enlarged by the conveying pressure such that comparatively largespecimen amounts may be processed. Furthermore, the buildup of pressurein the storage chamber 33 is reduced by way of the enlargement of thevolume.

The exemplary embodiment of FIG. 10b differs from the exemplaryembodiment of FIG. 10a in that there is a filling duct 38 that opensinto the storage chamber 33, through which filling duct 38 a reagent maybe filled into the storage chamber, for example by means of manual orautomatic pipetting, or by means of a needle that penetrates the fillingduct. It is to be understood that air that is displaced during thisprocedure must be able to escape from the storage chamber 33. Afterfilling, the filling duct 38 may be sealed by welding, adhesive bonding,or/and by means of a closure plug.

In the case of an exemplary embodiment that is illustrated in FIG. 11c ,a second duct 20′ having a barrier web 16′ is provided. The duct 20′ isconnected to the storage chamber 33 by way of a passage 39 which opensout above the fluid level of the fluid 34.

Once predetermined breaking points that are provided on the barrier webs16, 16′ have been ruptured, a specimen fluid may be infed by way of theduct 20 and of the pipeline 37, wherein displaced air may escape throughthe passage 39 and the duct 20′. By way of pressurized gas that comes tobear on the fluid level in the storage chamber 33 by way of the duct 20,a mixture of specimen fluid and reagent that has been formed may beremoved almost without residue from the storage chamber 33 by way of thepipeline 37 and the duct 20.

The plastics coating of the films 2 that are formed from analuminum-plastics laminate, as in the flow cells described above, ispreferably composed of the same plastics material as is the respectivesubstrate 1.

The fluid in the storage chambers described above, instead of being aliquid, may also be merely air or another pressurized gas that is usablefor transporting fluid in the flow cell.

The substrate, in particular on that side thereof that faces the film 2,is expediently provided with a surface structure, for example withtrenches, that facilitates the connection to the film 2, 3. The trenchesmay encircle the storage zone, in particular. Preferred cross-sectionaldimensions of the trenches are 0.1×0.1 mm² to 1×1 mm². One to threetrenches are advantageously formed. During adhesive bonding or welding,the adhesive or the fused plastics layer of the film 2 may penetrate thetrenches and engage therein, this improving the adhesion of the film tothe substrate 1.

In order for the cover film 3 to be connected to the substrate, inparticular laser welding or thermal bonding may be considered, evenbonding facilitated by solvents. Using this method, connection zones ofthe predetermined breaking points that have constant dimensions andconstant strength may be achieved.

1-16. (canceled)
 17. A flow cell, comprising: a duct; at least onestorage zone connected to the duct for transporting fluid from, into,or/and through the storage zone in a flow direction, wherein the ducthas a duct zone delimited by a substrate and by a film connected to thesubstrate, in the duct zone the duct is closed off and at apredetermined breaking point is openable while deflecting the film,wherein the film covers a clearance in the substrate that forms the ductzone; and a barrier wall disposed in the clearance and integrallyconnected to the substrate and shuts off the duct, the predeterminedbreaking point is formed by a rupturable connection zone between thefilm and a peripheral portion of the barrier wall that faces the film,dimensions of a peripheral area of the barrier wall that is parallelwith the film and is formed in the peripheral portion are relevant to aplanar extent of the connection zone.
 18. The flow cell according toclaim 17, wherein the peripheral area approximates a line that isperpendicular to the flow direction.
 19. The flow cell according toclaim 17, wherein the barrier wall is a barrier web that traverses theclearance, and said barrier web is connected to the substrate at ends ofthe barrier web and on the peripheral portion that is opposite theperipheral area.
 20. The flow cell according to claim 17, wherein thebarrier wall has a thickness that decreases toward the film, and thebarrier wall is configured to be triangular or segment-shaped.
 21. Theflow cell according to claim 20, wherein the barrier wall has aflattening that faces the film.
 22. The flow cell according to claim 17,wherein the peripheral area of the barrier wall that is parallel withthe film has a bulge that protrudes counter to the flow direction. 23.The flow cell according to claim 17, wherein the duct, in the duct zonethat has the predetermined breaking point, in relation to duct zonesthat are adjacent to the duct zone with the predetermined breaking pointin the flow direction, is widened or constricted in cross section. 24.The flow cell, according to claim 17, wherein the duct is rupturable bya fluid pressure that bears on the predetermined breaking point in theflow direction, or by way of mechanical or/and pneumatic deflection ofthe film.
 25. The flow cell according to claim 17, wherein the film atthe peripheral area of the barrier wall is adhesively bonded and/orwelded to the barrier wall.
 26. The flow cell according to claim 17,wherein the film is clamped to the peripheral area of the barrier wallby a movable clamping element that is connected to the flow cell. 27.The flow cell according to claim 17, wherein the substrate isplate-shaped and the clearance is open toward a planar area of theplate-shaped substrate.
 28. The flow cell according to claim 17, whereinthe predetermined breaking point lies in a projection zone of thestorage zone, the projection zone being for a projection perpendicularto a planar area.
 29. The flow cell according to claim 17, wherein theduct has a plurality of predetermined breaking points, wherein a dryingreagent is enclosed between two predetermined breaking points.
 30. Theflow cell according to claim 17, wherein the storage zone is delimitedby a thermoformed film on one side of the substrate, and is connected tothe duct zone by a duct portion, and the film that delimits the ductzone is disposed on the other side of the substrate.
 31. The flow cellaccording to claim 30, wherein the film that delimits the storage zoneis an aluminum-plastics laminate having a plastics layer that faces thestorage zone.
 32. The flow cell according to claim 30, wherein at leastone side of the substrate has a surface structure that facilitatesconnection to the film.
 33. The flow cell according to claim 32, whereinthe surface structure includes trenches.
 34. The flow cell according toclaim 17, wherein the film that delimits the duct zone is a plasticsfilm.
 35. The flow cell according to claim 17, wherein the plastics filmis covered by an aluminum-plastics laminate.
 36. The flow cell accordingto claim 29, wherein the film that delimits the duct zone is acontiguous film that delimits a plurality of storage zones.